Oscillating apparatus



2 Sheets-Sheet 1 E MAYER OSCILLATING APPARATUS Flled Jan 9, 1924 Jan. 1,1929.

Current INVENTOR EMIL MAYER.

BY WWW ATTORNEY Jan. 1, 1929. 1,697,126

E. MAYER 0s CILLATING APPARATUS Filed Jan. 9,1924 2 Sheets-Sheet 2INVENTOR EM I L MAYER ATTORN EY Patented Jan. 1, 1929.

UNITED STATES PATENT OFFICE.

Em MAYER, OF BERLIN, GERMANY.

osorua'rme arrana'rus'.

Application med Ianuary9,'1994, Serial No. 685,211, and in GermanyOctober 16, 1923.

This invention relates to an improvement in oscillating apparatus, foruse in radio and other electrical circuits; and particularly oscillatingapparatus adapted .for modulating 5 and receiving purposes.

An object of the invention is to provide an oscillating device whichwill operate through an ordinary electrical valve device havingterminals comprisin a cathode and a pair of l anodes; the anodes heingso related that the action of one of them, for example the grid, uponthe other, for example the plate, is ea-tly increased by automaticmeans, which influences the relations between these two 1 members so asto produce the desired result.

Preferably I achieve my purpose by causing the well-known controlling orback-feed action of the grid to be modified by having the phase of itsvoltage changed with respect to the voltage of the plate. This variationof phase can be accomplished in accordance with this invention by theuse of reactance means such as an electro-magnetic element in the platecircuit, or the grid circuit or both, which controls the current andoscillations in the plate circuit or grid circuit or both, andperiodically or in accordance with the signals impressed afiects theback-feed action or controlling action of the grid in such a manner thata greatly enhanced output or ampl fication per stage in the platecircuit 18 obtained.

In like manner my invention can be practiced with all means forproducing oscillations comprising an output circuit and a circuit tocontrol same.

Other objects and advantages of this inventi on are set forth in thefollowingdescrip tion, together with the drawings which show electricalconstructions by which my invention can be practiced, and the novelfeatures of my oscillating arrangement are defined 1n the appendedclaims. This disclosure, however, is illustrative only, and I may changethe details of what is actually presented in the drawings withoutdeparting from the principle of this invention, to the full extentindicated ,by the broad and general meanings of the terms in which theclaims are expressed.

In the drawings Fig. 1 shows diagrammatically a circuit comprisingterminals. such as a cathode and a pair of anodes, the latter beingconnected in controlling or feed-back relation, with an electromagneticelement in the circuit of one pi the anodes in accordance with myinvenion;

F 1g. 2 presents a graph showing the effect produced by the presence ofthis electro-magnetlc' element; Fig. 3 presents a pair of diagrams to indicate the manner in which the feedback action of one of the anodes ismodified and its phase altered by the presence of this element; Fig.shows a complete oscillating device or aumt;

Fig. 5 shows a circuit for receiving purposes in telephony, according tomy invention, with key to transmit signals included, if desired; and

Fig. 6 shows how two or more oscillating devices can be connected incascade to make a complete amplifying apparatus or system in which theprinciple of my invention is embodied.

The same numerals identify the same parts throughout.

Referring first to Fig. l, I show an ordinary electrical oscillating orvalve device consisting of a simple vacuum tube having a plate 2connected with reactance means, such as a self-inductive coil 3; thisplate having its circuit completed through a conductor 4 leading to oneterminal of a. filament 5 in the tube, this filament being connected tothe usual energizing battery A. Connected around the coil 3 is acondenser 6. The tube also contains a grid 7, which is joined through aconductor 8 to a coil 9 that may be loosely coupled to the coil 3 andlikewise united to the wire 4., so that the grid circuit or controllingcircuit extends from member 7 through the filament, the conductor 4, thecoil 9 and the wire 8. Contraryto the usual practice, ll provide theplate circuit with an iron core 10, associated with the coil 3, and Ibelieve the presence and the action of this core to be new. Betweenthegrid and the coil 9, ll may have an inductance coil 11, and the gridcircuit also has a condenser 12 between the grid and the filament 5. Theiron core 10 can be so designed with reference to the frequencies to begenerated in the circuit of the plate or anode 2, that the operationwill be attended with only small losses. Hence I employ finely laminatedsheet iron for this core or very fine iron wire when very hi frequenciesare to be obtained. At B is the battery for terminal 2, and a'coil 13with iron core may be inserted between this battery and the plate, toprevent oscillations reaching the battery B.

'We may now consider, independently of the tubel, the characteristics ofa circuit comprising a condenser and a self-induction coil with an ironcore. When oscillations are produced in such a circuit, the naturalperiod of or number of oscillations in 1t is not constant, because theself-induction of the coil depends upon the degree of saturation of theiron. Thus the number of oscillations is variable and changes accordingto the degree of momentary magnetization which exists or is produced bythe influence of the current flowing in the oscillation circuit. Thegreater the current the smaller becomes the self-induction and thegreater becomes the number of oscillations or frequencies.

Fig. 2 presents a pair of axes, OX and OY, and the curve OM is thewell-known curve of magnetization produced by a current flowing around acore of iron. The OY axis will give, for constant frequency, the voltagebetween the terminals of the coil 3, depending upon the current flowing,which is plotted along the OX axis; while a straight line extending fromthe point 0 to any point of the curve gives the voltage between theterminals of the condenser. Since the circuit works at the naturalfrequency, the voltage of the inductance coil 3 and the condenservoltage must be the same, no matter what the current. Therefore theslope of the line from the point 0 to any point on the curve OM givesameasure of the generated fre quency per second. Obviously as we go romthe point O along the line OM with increasing current, a line from theoint O to successive points along the line N makes a decreasing anglewith the horizontal axis, and the cotangent of this angle, as the slopeof the line decreases, will increase. Hence increasing the current up toa certain point will cause a material increase of frequency to takeplace.

With this in mind, one will see, with reference to Fig. 1, that when thetube 1 is working so that current will flow in both the plate circuitand the grid circuit in the well-known manner so as to produceoscillations in the plate circuit, the number of oscillations orfrequency in the plate circuit will change from the moment theseoscillations begin, according to the amplitude of the current in thecoil 3. It is to be assumed that the self-induction produced by the coil3 containing the iron core 10 is so designed that when current flows inthe coil 3, a suitable range of the curve of magnetic saturation will betraversed.

For example, the grid or controlling circuit in Fig. l which is inback-feed relation to the plate circuit through the loose couplingbetween the coils 3 and 9, will be so designed and tuned that forthe'initial oscil-- lations and a very small load or output of the tube1, this circuit will be almost entirely self-inductive in character.Under these circumstances, the condenser 12 of the grid circuit willhave a slight eflect. The natural number of oscillations or frequency ofthe grid circuit, too, is smaller than the natural number ofoscillations of the plate circuit.

The core 10 is now in a condition of slight or low saturation. However,as the oscillations continue, the current rises and increases inamplitude in the plate circuit of the tube. The iron core 10 becomesmore and more saturated, with the result that the effectiveself-induction in the plate circuit grows less, and consequently thenumber of oscillations in the plate circuit become greater.

Now the back-coupling to the grid circuit is correct and efiective solong only as, with the oscillations generated, the grid circuit remainspreponderantly self-inductive. But as soon as, in consequence of theloading or saturation of the iron core, the frequency so increases inthe plate circuit, that with a corresponding increase of frequency inthe grid circuit through the coupling between coils 3 and 9, a point isreached at which, in consequence of this rise in frequency, resonance isattained-and passed, the phase in the grid circuit changes, and thiscircuit becomes capacitative in character. The phase of the voltage ofthe grid, as is well known, will alter very quickly with respect to theplate voltage by almost as much as 180. Now the back-coupling whichformerly produced oscillations causes a choking of oscillations. Thechange of conditions in the grid circuit whereby, upon the point beingpassed at nance and the character of the grid circuit becomes changed,is indicated on the two diagrams of Fig. 3,. the lower of these twodiagrams presenting a condenser O in the place of the coil 9, in orderto stress to the eye the point under discussion. The efiect so obtainedcan be utilized according to this invention in many ways, and givesamplification in very high degree. What really is attempted andaccomplished is the same as though the tickler coil commonly used andwell known were rapidly thrown over from a back-feed to a contraryposition.

In practice, the reversal of the phase of the voltage in theback-coupled grid circuit in consequence of theincreasing magneticsaturation of the iron core 10, must not be allowed to take place slowlybecause a certain stability of oscillations generated may occur; but onthe contrary, such reversal of the phase should take place quickly. Theplate circuit and the grid circuit must be so designed in relation toone another that fore it can begin to increase again.

influence of the signals.

takes place, is arrived at b the use oi a surlus of energy, for examp e,by malrmg the back coupling in such a way that oscillations begin veryquickly and the critical point is reached before the full capacity ofthe tube is used. Then no stability results. 11 the contrary, after theattainment of the critical'point, and the corresponding degree ofsaturation of the iron, the current inthe plate circuit will risesomewhat further and then rapidly drop, after the chin e of phase takesplace in the grid circuit, an in consequence of the change of phase.

Due to the hysteresis in the iron at decrease of current, the point atwhich the pscillations or frequency in the grid circuit runs through thecritical or resonance point in reverse direction, is reached at muchlower current amplitude. In fact, by proper design, one can make thecurrent in the anode or plate circuit completely die out or sto 'beence,instead of stable oscillations with constant amplitude of current in theplate circuit, a periodical change of the amplitude takes place. Theperiod of this change of amplitude depends, as is easily seen, upon thecon stants of both circuits, and particularly upon the resistance in theplate circuit and the steepness with which the oscillations of the tubestart, that is to say, of the back coulin A simple and practicalutilization of the phenomena above set forth can be made for receivingpurposes in both wireless telegraphy and telephony. In telegraphy, forexample, I can utilize the principle of my 1nvention in connection witha circuit for the reception of undamped signals, in place of theheterodyne receiving circuit, and reater sensitiveness can easily besecured. lie tube 1 is then so operated that with no voltage impressedupon the grid from without, oscillations commence. The signal thusproduces the oscillations and the eiiect oi the iron core audiblymodulates the signals.

The auxiliary frequency then introduced can be enhanced by providing inthe plate or output circuit, or in the grid circuit, or in both, anelement which is tuned to this auxiliary frequency. For instance, onecan place one or more auxiliary windings upon the coil 3 with the core10, and with additional means, such as coils and condensers, make aresonance circuit for the auxiliary frequency, and back-couple thisauxiliary resonance circuit, which may include a similarly tunedelement. The auxiliary frequency comes from the interruptions, due tothe iron core 3, of the oscillations produced by the valve under theSee, for example, Figure 4. In this view the connections are all as inFigure 1, with the addition that an auxiliary winding 14 is which theincomin placed u on the coil 3, and in .circuit with this win ing arecoil 15 and condenser. 16, (variable if desired), which will be tuned tothe auxiliary frequency, which is diiferent i from the frequency of thesignal oscillations. Included in the grid circuit may be a con denser 17united by conductors 18 to a coil 19, that is to carry theauxiliaryjrequency only, the coil 19 being in inductive relation to thecoil 15. By means of the coil 19 and condenser 17, theefiect of afurther backcoupling is rovi'ded for the circuit of the gri or mem r,and this further back-coupling may be either tuned to the auxiliaryrequency or aperiodic, and either capacitative or inductive.

Forreceiving purposes in telephony, the tube is set to oscillate at thefrequency of the incoming signals. It is very easy to adjust theperiodic change of theplate current, then, to take place at a frequencyabove audible limits. If, now, the coil 11 becoupled' to an antenna andincoming signals received upon it, and the tube set into operation, theincoming voltages will be im ressed upon the grid circuit. The combineaction of the feed back, and the incoming signals, and further possibleback-feed provided by parts 17 and 19, will modulate the output of theplate circuit, in accordance with the eli'ects signals produce in thecoil 11. A degree 0 amplification in the tube is thus obtained which islimited only by the available output capacity of the tube, and is almostcompletely utilized for the generation of the sounds in the telephonereceivers.

A further arrangement according to my invention with the coil 11 coupledto an antenna clrcuit is presentedin Figure 5. Here a telephone receiveris shown in the plate circuit at T. The extra back coupled circuitcomprising the condenser 17 and coil 19 is omitted and a coil 9 isutilized inplace of the coil 9, in inductive relation to the coil 11; i.e., as a tickler coil being connected to one terminal oi the coil 3 andto one terminal of the filament. Except for the omission of theadditional back feed, due to condenser 17 and coil 19, the operation ofthis arrangement, as to the efiect of the coil 3 with iron core 10, isthe same as above. In parallel with the coil 11 is shown an adjustablecondenser 12, with another adjustable condenser 20 between the plate andfilament, and the condenser 6 in series with the coil 3. It will benoted that in Figs. 1, 3 and 4: condenser 6 is shown in parallel withwinding 3,whereas in Figs. 5 and 6 condenser'G is disposed in serieswith coil 8. At a is shown the antenna with coil P in inductive relationto the coil 11. This circuit is untuned and operates to givesuper-regenerative amplification. Y

My invention can also be advantageously used by feeding the incomingsignals into the llti modulating coil placed on the iron core selfinductance of the plate circuit of the tube, instead of feeding it intothe id circuit.

Figure 6 gives a working ia 'ram of this mode of operation. In order too btain a high amplifying effect, the tube and the saturation of theiron core of the coil are so set that a minimum change of saidsaturation will produce a large change in the amplitude of the plateoscillations by changing the phase relation between the grid and theplatecircuits.

At the left half of Figure 6, the condenser 12 is across filament andrid. Variable oondenser 20 is connected asliefore, and the terminals ofcoil S inductively related to the antenna, are joined to the circuitincluding the parts 14:, 15- and 16. Condenser 6 is in series with coil3, and coil 9, though still loosely coupled to coil 3, has a biasbattery 0, to infiu ence the grid circuit, so that the variation ingscillations has the maximum'rectifying ef set.

It is advantageous to set the grid bias so that the maximum change inplate current will be obtained for a certain change of the amplitude ofthe plate oscillation.

The output of the tube can for purposes of further amplification be fedinto another unit made up in the same way, as shown at the right half ofFigure 6. This is accomplished by connectin the plate and filament atthe left half of igure 6 to a second unit of the same description as, atthe left half of Figure 6; running the conductors 21 from late andfilament as before to the circuit 0 the condenser 16 and coils 15 and 1dof the second unit. Goil 15 may have an iron core 22, and in the circuitleading from the first unit to the second may be a battery B and areceiver T in series with the coil 15. Another coil 23, with iron core24, in series with another battery l3 and receiver T, will be in theplate and filament circuit of the second tube. This sec ond receiver maybe operated at audio frequency, while the first joined to the unit atthe left, enables the operator to ascertain conditions in the first orleft unit, and adjust accordingly.

Depending upon the frequency to be amplified, it may then be decidedwhether the current fed into the second unit be the rectified current ofthe first unit as shown in Figure 6, or whether the feeding is donedirect at the frequency generated in the first unit. In the latter case,the input circuit of the second unit at the right can be tuned similarto the first unit. If the frequency received be high, it may even beadvantageous to rectify before going into the input circuit of the firstunit.

My invention will work very well also, if the tuning of the grid circuitbe changed in accordance with the signal instead of the tuning of thecircuit of the plate or anode terminal 2, and if by these means thephase relation between the two circuits is shifted in the way described.Thismay be advantageous inasmuch as much smaller currents flow in thegrid circuit than in the plate circuit.

For the utilization of the full effect of the invention for receivingpurposes, one may employ a receiving tube with larger emission than iscustomary. Such larger emissiv'e capacity can be obtained by the use ofoxide covered 'filaments in the tubes, without too much powerconsumption for the heating of the filaments.

To facilitate the tuning of such apparatus and ive a very closeadjustment of the point at w ich phase alteration takes place, one canarrange to give the iron 10 a variable preliminary magnetization withdirect current, but the circuit of this direct current must of course beprotected against high frequency. See Figure 5, showing a smallmagnetizing coil 25 on the core 10, in circuit with a battery =M,iron-core choke coil 26, and variable res1stance 27.

A further advantage in the use of this invention is due to the fact thatit permits the making and breaking of large energies with small means.in transmission, if a tube is operated so as to be in stableoscillation, the greater part of its selfinduction being, however,provided with an iron core, one can use a small direct current in theauxiliary winding, and thus change the self-induction. Thus verysuddenly the false phase of the voltage in the back coupling isproduced, and the oscillations are very rapidly choked. For this purposea key K can be provided, as shown in the circuit of battery as in Figure5.

Figure 6 shows how my invention can be employed in cascade. in thiscombination,

the first coil 14 is joined by wires 21 to'a coil S, which is part of areceiving antenna P. The output circuit of the first tube is con nectedto a second unit and the output of the first tube is further amplifiedby the action of the second tube, and so on until the desired degree ofamplification is reached. The device as shown in this view has theadvantage, that in succeeding steps of amplification the frequencies canbe chosen arbitrarily and differing from each other, provided that eachone of these frequencies is higher than the frequency of its input.

The vertical dot-and-dash line in Fig. 6 signifies that no inductiverelation exists between the coil 15 of the first unit and the adjacentcoil 11 of thesecond unit.

A further advantage is that there is no reradiation, because only theantenna and first input circuit are tuned to the signals.

Of course any magnetic metal besides iron can be used for the core 10.

While I have described my invention in certain preferred embodiments, lldesirethat it be understood that modifications may be made and that nolimitations upon my inven-- tion are intended other than are imposed bythe scope of the appended claims. Having described my inventign what Ibelieve to be new and desire to secure and protect by Letters Patent ofthe United States is: 1. Radio receiving apparatus comprising anelectrical oscillating device having an out put circuit, a member forco-operating with said circuit, to be subjected to an electricpotential, an electro-magnetic means connected in shunt with saidcircuit and capable of changes in reactance to influence the phase ofthe voltage of said member with respect'to thevoltage in said circuit tocause amplifying action, said changes in reactance depending on valuesof current passingtherethrough, and means for cont-rolling'the-efl'ectof said electro-magnetic means in accordance with incoming oscillations.

2. An amplifying device comprising an electrical valve devicev having aplate filawith ment and grid therein, an output circuit connected withsaid plate, a grid circuit connected in feed-back relation to the plate,and an inductive coil with magnetic core connected in shunt with theplate and filament to influence the phase of the voltage of the grid ctto the voltage of the plate, and" an auxiliary coil for fixingthemagnetic condition of the first coil. V I

3. An amplifyin apparatus comprising an electrical valve evice having aplate and an output circuit connected thereto,ja grid circuit connectedin feed-back relationto the plate, an electro-ma etic'coil connected inshuntto the output circuit, said coil having a magnetic core, theinductive efiectof said coil influencing the phase of the voltage of the40 grid circuit with respect to that ofthe plate circuit, an auxiliarycoil in inductive relation to said coil, and connections for enablingsaid auxiliary coil to receive 'incomin signals for changing the maetic'conditlon of said first mentioned coil or modulating the output ofsaid valve device.

4. An oscillating device comprisin' a late,

a'filament and a grid electrode, circults interconnecting saidelectrodes, a coil with magnetic core connected in shunt with the lateand filament, the grid being in feed-bee relation to the plate, anauxlliary coil inductively related too the first coil, means comprisinga coil and a condenser connected to the auxiliar coil, and an additionalcoil associated wit the auxiliary coil and connected to provideindependent control of the grid circuit.

5. A cascade amplifier consistin of successive units, each com rising anosc lating device with a termina connected to an output circuit andreactance means in each output circuit, a controlling circuit associatedwith electron tubes each having rid,

.tron tube an a winding on said core disposed in shunt with said outputcircuit and a magnetic .coupling between said winding and one of saidcircuits.

7. A vacuum tube comprising a plate circuit and a grid circuit, saidgrid circuit being connected 1n feed-back relation to said platecircuit, means connected in shunt with the plate circuit of said tube toalter the phase relation of the currents in said circuits, and

auxiliary means magnetically coupled with said first mentioned means forselectively fixing the magnetic condition of said plate circult.

8. In an amplifying system a Iplurality of plate electrodes, input anoutput circuits interconnecting said electrodes, a signal receivingcircuit, means couplin the input circuit of one of said electron tu eswith said signal receiving circuit, a circuit connected across theoutput circuit of said last mentioned electron tube and comprising aseries connected inductance and capacity, an iron core for saidinductance, an auxiliary winding disposed on said iron core, atunedcircuit connected with said auxiliary winding" and connections betweensaid tuned circuit and said signal receiving circuit, a con ling betweenthe in ut circuit of a succee ing elecsaid last mentioned tuned circuitand a responsive device connected in the output circuit of said lastmentioned electron tube.

'9. An amplification system comprising a lurality of electron tubes eachhaving grid,

filamentand plate electrodes, in ut and output circuits interconnectingsai electrodes, the output circuit of each of said tubes including ashunt circuit having capacity and inductance elements therein, an ironcore for each of said inductance elements, an auxiliary circuitassociated with each of said inductance elements, inductances in theinput circuits of each of said tubes coupled with the inductanceelements in said shunt circuits and a coupling between the input circuitof a succeeding tube and the auxiliary circuit of a precedin tube.

In testimony whereof I afllx myfsAi%ture. EMIL R.

lament and

